1. J-modulated 13C spectdra. The pulse sequence previously devised has been used to differentiate the methylene groups of limonene. 2. Dendrobatid alkaloids. a. A skin toxin of a toad, Melanophyriscus spp., has been shown to be a hydroxy derivative of the alkaloid 251D, isolated from a dendrobatid frog. b. The stereochemical relationships of the 7-hydroxypumiliotoxins have been clarified. 3. Metabolic products of arylhalides. The product of the action of liver microsomes upon p-bromophenol has been shown to be 6-glutathionyl-4-bromocatechol.